1. Field of the Invention
The present general inventive concept relates to an image forming apparatus, and more particularly, to a developing cartridge and an electrophotographic image forming apparatus equipped with the same.
2. Description of the Related Art
A general electrophotographic image forming apparatus prints a desired image through a process in which a photosensitive medium is exposed in a predetermined pattern to form an electrostatic latent image, a developer is deposited on the electrostatic latent image, and the developed image is transferred onto a paper.
FIG. 1 schematically shows a conventional electrophotographic image forming apparatus 100.
As shown in FIG. 1, the conventional electrophotographic image forming apparatus 100 comprises an exposure device 110, a developing cartridge 120, a fixing device 140, and a paper feeding device 150. When a printing signal is externally inputted, the exposure device 110 illuminates a laser beam onto a photosensitive drum 124 (FIG. 2) in such a way that an electrostatic latent image is formed on a surface of the photosensitive drum 124. The electrostatic latent image formed in this manner is developed by toner into a toner image, and the toner image on the photosensitive drum 124 is transferred by a transfer roller 130 onto a paper fed from the paper feeding device 150. Then, the transferred toner image is fused on the paper when the paper passes through the fixing device 140.
The developing cartridge 120 is a kind of consumables having a limited lifespan and detachably mounted on an image forming apparatus body 160. FIG. 2 schematically illustrates the conventional developing cartridge 120. Referring to FIG. 2, the conventional developing cartridge 120 comprises a casing 121, a toner storage chamber 121a, a toner feeding chamber 121b, a developing roller 122, a feeding roller 123, a photosensitive drum 124, an electrification roller 125, and a waste toner collecting chamber 121c. The storage chamber 121a fluidly communicates with the toner feeding chamber 121b, and the toner feeding chamber 121b is open to allow a toner to move to the photosensitive drum 124. In addition, an opening formed between the toner feeding chamber 121b and the photosensitive drum 124 is closed by the developing roller 122, a restraint blade 126 and a shielding blade 127. However, the shielding blade 127 is apt to be deformed by pressure of toner charged in the toner feeding chamber 121b and the toner storage chamber 121a. Further, if an impact is applied to the developing cartridge 120 or vibration occurs in the developing cartridge 120, a gap is formed between the developing roller 122 and the shielding blade 127, through which the toner may leak out. Due to this problem, the conventional developing cartridge 120 is marketed in a state that a shielding member 128 closes the toner storage chamber 121a. 
However, with the conventional developing cartridge 120, since a space for storing toner is limited to the interior of the toner storage chamber 121a defined by the shielding member 128, the toner storage quantity is restricted. As a result, the developing cartridge 120 needs to be often replaced. Furthermore, since components of a developing cartridge, such as the photosensitive drum 124 and the developing roller 122, are being improved in endurance recently, accommodation of the toner needs to be improved in order to lengthen a life span of the developing cartridge 120.
In order to solve this problem, the size of the toner storage chamber 121a may be enlarged. However, it is not a desirable method because an image forming apparatus body should be also increased.